Wu Xiao, Yan An, Yang Xi, McAdam Scott A M, Liu Xing, Zhang Shaoling, Zhou Yun
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907.
Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907.
J Exp Bot. 2025 May 13. doi: 10.1093/jxb/eraf206.
Meristems in land plants serve conserved functions, maintaining undifferentiated cells and continuously producing new cells to support organ development and body formation. In seed plants, de novo meristem formation involves the initiation and assembly of new stem cell niches, promoting organogenesis and shaping plant architecture. However, the function and regulation of de novo meristem formation in seed-free vascular plants remains largely unknown. Unlike seed plants, which have highly reduced gametophytes within a sporophyte-dominated life cycle, fern gametophytes develop pluripotent meristems that sustain growth independently of their sporophytes. Unlike the gametophytes of terrestrial ferns, epiphytic ferns exhibit programmed clone-forming or clonal growth during the gametophyte phase, suggesting enhanced or prolonged meristem activity. Using confocal live imaging with computer-assisted image segmentation and quantifications at single-cell resolution, we show that in Phlebodium pseudoaureum, a representative epiphytic fern, continuous de novo meristem formation drives gametophytic clone-forming and extended longevity. Patterns of cell growth and division are closely associated with the initiation and expansion of de novo-formed meristems in Phlebodium gametophytes, with active proliferation in the outermost layer driving this process. Our findings uncover the cellular basis of de novo meristem formation in epiphytic ferns and highlight both conserved and lineage-specific mechanisms controlling meristem initiation and proliferation in land plants.
陆地植物中的分生组织具有保守功能，维持未分化细胞并持续产生新细胞以支持器官发育和植物体形成。在种子植物中，从头分生组织的形成涉及新干细胞龛的起始和组装，促进器官发生并塑造植物结构。然而，无种子维管植物中从头分生组织形成的功能和调控仍 largely 未知。与种子植物不同，种子植物在以孢子体为主导的生命周期中配子体高度简化，蕨类植物的配子体发育出多能分生组织，其生长独立于它们的孢子体。与陆生蕨类植物的配子体不同，附生蕨类植物在配子体阶段表现出程序性克隆形成或克隆生长，表明分生组织活性增强或延长。使用共聚焦实时成像结合计算机辅助图像分割并在单细胞分辨率下进行定量分析，我们表明在一种代表性的附生蕨类植物——假金叶书带蕨中，连续的从头分生组织形成驱动配子体克隆形成和延长寿命。细胞生长和分裂模式与假金叶书带蕨配子体中从头形成的分生组织的起始和扩展密切相关，最外层的活跃增殖驱动了这一过程。我们的研究结果揭示了附生蕨类植物中从头分生组织形成的细胞基础，并突出了控制陆地植物分生组织起始和增殖的保守机制和谱系特异性机制。
